Ah, that's the cause of your troubles. As mentioned in the feature listing, Express requires OSX 10.5 or later to import .docx files. However .doc files should be imported on OSX 10.4, so that seens like a problem we'll have to look into.

In the meantime, I might recommend Express version 3.3.2 which does not have this issue with .doc files (though it still won't open .docx files on OSX 10.4), or use Nisus Writer Pro which does not rely upon OSX for either .doc/.docx file import (and actually does a better job).

Also, I cant get the preferences to change to English UK. Is this because its just the trial version?

No, there are no limitations in the trial version. I'm not sure exactly what you mean when you say you can't get your preferences to English UK. Most likely you're confused as to how languages work in Nisus Writer.

In Nisus Writer languages are like fonts, eg: you apply languages to text. Each bit of text in a document can have a different language applied. So there's no global language preference exactly (though you can set the default language for any new files you create). You'll probably want to read this FAQ entry: